why are my rockets going rogue!?

[Zeekin]

So, trying to make a kind of heavy-lifter type rocket, got some of those rockomax tanks in an asparagus type formation, when I didn't have the command-module like extension it worked fine, now that I added a little more mass to the front I can't get out of the atmosphere now that my rockets decide to split... For the life of me I cannot figure out why they decide to go rogue on me, no matter how many struts I use, the same rockets decide it's time to get outta here.

I made a vid to show my design & what I'm talking about.. so very very frustrating.

On a side note, I have KSP installed on an SSD and my computer is a beast so I don't think it's related.

[Akalaël]

Strange indeed... What does say the report mission ?

It seems you have a structural failure , but with all the connecting structure you added I don't understand.

I use this Template for my launchers, and it is enought to prevent this kind of problems :

[Dictator Dan]

That central tank could use some reinforcement. Try a small cubic structural strut on both the top and bottom tank, and a strut between them. As well as some struts connecting the asparagus tanks to the girders. as it looks like thats where the tanks separated from your rocket.

[Nibb31]

Looks like a structural failure. Look at the flight log to find out which parts break first.

[Dictator Dan]

(Sorry for the extra post, but still under the forum nazis until I reach the post threshold, post forum burning)

Instead of that girder set up, try the TT-70 Radial Decouplers, they hold your extra tanks away from your central tank, reduce part count, and have a decent strength to them.

[blspblackdeath]

I guess it is a structural failure, too. Your thrust seems too high so the struts are breaking. Try to reduse your thrust to 75% or less after your first staging or more struts. ;-)

[Akalaël]

I had an other look at your vid.

I think part of the problem comes from the Structure you put on the radius orange tanks. The linkage here is maybe weak.

I just tried this :

500 m/s at 10km, more than 10g near 20km... nothing moved

[Splode]

Why are those radially attached engines so far out? Couldn't you bring them closer?

It'd be a lot less wobbly that way.

[sporkafife]

Maybe the thrust was too high on takeoff and that broke some vital structural links. The big orange tanks are known to be pretty buggy in their strength and things attaching to them. Does it still freak out and destroy itself if you throttle it down and take off more slowly?

[magnemoe]

Why are those radially attached engines so far out? Couldn't you bring them closer?

It'd be a lot less wobbly that way.

Yes, use the radial decopler with built in struts, put an seperatron or two on the booster to get it away.

[thoosequa]

I agree with the others here. I have a rocket design on which I have solid fuel rocket boosters attached to the rockomax fuel tanks. Whenever I throttle the rockets on the rockomax two much up the solid fuel boosters just turn a bit too much in, eventually crashing into my command module. Try reducing the speed to two thirds throttle during the first stage. The difference between 75% and 85% throttle should not affect your ascend, but it may affect the direction your boosters point.

[billyoak]

Hey mags,

How much mass are you trying to lift into orbit(also what orbit would you like 70km?) i could make a launcher for you.

billyoak

Edited May 2, 2013 by billyoak

[Zeekin]

I tried many of the suggestions and failed many times, I finally got something working which borrowed the radial separator idea from akalael, and ditched the orange tanks in favour of the grey ones.

I put in some supporting beams and strutted the entire craft so it was as rigid as possible. I think what might have been happening was that even though it looked stable on the outside there was massive wobble/shear from the top end being wobbly kind of like if you try to balance empty soda cans on top of each other.

[Vanamonde]

I suspect that 1500-thrust engines on the ends of those structural bars were exerting a lot of force not just from the engine thrust itself, but the vibrations of the engine gimballing would also be acting across the lever of the structural pieces' length, and they have a rather low failure limit. I think your ship was shaking itself apart.

[Krizzen]

I agree with Vanamonde. The engines gimbaling add a lot of unnecessary force. In fact, I had a design similar to the original you posted. I had the same issues -- a few random rogue rockets. I don't think the orange tanks connect well to girders. I wish I could remember how I solved my issues exactly, but I think it involved a combination of different girder/decoupler configurations and fewer struts connected further to the extremes of the fuel tanks.

[jordanjay29]

I agree with Vanamonde. The engines gimbaling add a lot of unnecessary force. In fact, I had a design similar to the original you posted. I had the same issues -- a few random rogue rockets. I don't think the orange tanks connect well to girders. I wish I could remember how I solved my issues exactly, but I think it involved a combination of different girder/decoupler configurations and fewer struts connected further to the extremes of the fuel tanks.

If gimbaling is the problem, then why not disable engine gimbal and use control surfaces/winglets to make course corrections while in atmosphere? At least until the last outer stage is dropped and there's less risk of the rocket falling apart.

[Elemental]

Becaus they have higher DPS....

[M5000]

inb4 Temstar shows people how to properly build lifters.